1. Field of the Invention
The invention relates to a method of manufacturing methylidene-group-containing .alpha.,.omega.-unsaturated oligomers from .alpha.,.omega.-diolefins in the presence of organoaluminum compounds as catalysts, and to compositions produced by this method.
2. Discussion of the Background
It is known that .alpha.-olefins when heated with catalytic amounts of trialkylaluminums or dialkylaluminum hydrides react to form mixtures containing a predominance of .beta.-branched .alpha.-olefins having twice the number of carbon atoms compared with the initial olefin. For example, the main product in the dimerization of propene is 2-methyl-1-pentene and the main product in the dimerization of 1-butene is 2-ethyl-1-hexene (see German Pats. 878,560 and 925,291; also 629 Liebigs Ann. Chem. 121-166 (1960)).
When the above reaction is employed with hydrocarbons having two terminal vinyl groups (.alpha.,.omega.-diolefins), the principal products isolated are cyclic. Thus, butadiene results in a mixture of methyldimethylenecyclopentanes (U.S. Pat. Nos. 3,356,704 and 3,391,209; 1969 J. Org. Chem., 34, 1931-1935), and 1,5-hexadiene and 1,6-heptadiene are cyclized to methylenecyclopentane and methylenecyclohexane, respectively (70 Angew. Chem. 862-863 (1967) ; 1976 Tetrahed. Lett., 1257-1258). The same observation was made in studies of bis-hydroalumination of .alpha.,.omega.-diolefins (28 J. Org. Chem. 3237-3238 (1963)). There was only parenthetic mention of the production of small amounts of higher homologs from the .alpha.,.omega.-diolefins, which was not the stated purpose of the synthesis. Methods of manufacturing polymeric hydrocarbons starting with .alpha.,.omega.-diolefins and using organoaluminum compounds as catalysts are not known.